KonsortSWD Measure 5.1: metadata schema extended report

The persistent identifiers (PIDs) assigned to the level of attributes, i.e., a variable in Social Science research data, can unambiguously cite and direct retrieve data. Variables change through the studies' timeline and promote cross-linking through the survey waves, studies, and other entities such as questions and concepts among questionnaires. Given the importance of variables and their ties, the associated metadata has to register such relations and allow machine actionable features through PIDs and controlled vocabulary terms. The KonsortSWD "Measure TA.5-M.1 Enhancing PID services as a base for a FAIR data infrastructure" outputs a PID registration widening of the da|ra service to assign PIDs. The basic metadata schema was extended to meet the increasing demand for interoperability, data mappings, and knowledge graph. This solution comprises a metadata schema for the persistent variables identification and cross-linking relations.